Bill Eyring – CNT Senior Engineer

Illinois Sustainable Technology CenterSeptember 29, 2010

Monitoring and Documenting Green Stormwater Best Management Practices

The Center for Neighborhood Technology

32 year old Chicago-based non-profit

Sustainable energy, transportation, natural resource, climate strategies: Research Advocacy Demonstration projects Scaling up, replication

Green Infrastructure agenda Planning/Analysis Toolbox Policy Education Practice

Project History with Hey and Associates

• USEPA Project – 2007-2008– 2 bioswales, 2 rain gardens

• IEPA Project – 2007-2008– 2 rain gardens, 1 vegetated swale

• ISTC Project • Related Activities

– Rain garden demonstrations– Policy analysis and advocacy– Illinois EPA and legislature

Calumet Bioswale

• Constructed in 2007 with USEPA funding

• Monitored from Oct. 2007 to the present

• Size: 10 by 66 feet• Drains 12,433 sq.ft.• Repair of outside

drain recently completed

Results in 2010 and before

• Infiltration rates of 0.2 to 0.8 inches per hour

• Infiltration rate of the swale is limited by the infiltration rate of the subsoils

• Performance satisfactory for events up to 0.5 inches

• The swale has until recently been receiving overflow from the adjacent sewer system during events over 0.5 inches

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Surface Water Level Aggregate Water Level Subsurface Water Level 5-minute Rainfall

Rogers Park Pervious Concrete

• Constructed in 2008 with USEPA funding

• Monitored 2009 to present• Two 15 by 15 ft. patches in

8,704 sq.ft. parking lot• Infiltration Rates of 1.08-

1.31 in./hr when clogged• Surface Infiltration

Capacity of 33.2-88.3 in./hr.(ave.57.87) after washing and 6.01-63.80 (ave.38.35) after winter

Bellwood Rain Gardens

• Constructed in 2008 with IEPA funding

• Raingardens of 220 and 230 sq.ft.

• Roof drainages of 1,340 and 1,540 sq.ft.

Results in 2009

• Infiltration Rates– Turf grass = 91.3 in/hr– Native = 3.3 in/hr

• Additional infiltration testing under way

• Rain gardens leak during storm events

• Weir coefficients have been calculated for the installed weirs

Benefits of a G.I. Inventory

• The City of Chicago is stalled on an inventory

• The MWRD needs to hear about green infrastructure extent and performance

• Engineers and regulators are eager for information

• Costs and performance vary widely and need to be communicated

Benefits of Expansive Assessment

• Monitoring is high cost, weather dependent and limited to a few sites

• BMPs range greatly in size, complexity and cost, so many samples are better

• Inventory and assessment leads to more implementation

• A variety of audiences will be interested in the results and able to act on them

Inventory of Existing BMPs

• Email requests to 200 potential informants with request that they share with others

• Personal reminders to best sources• 160 facilities so far with many more coming

– 57 rain gardens– 21 permeable pavement– 17 bioswales– 8 green roofs– 5 water harvesting systems– 52 other

Assessing Rain Gardens

• Visual Assessments– Hydraulic Conditions– Vegetation– Soils

• Infiltration Rate Testing

• Synthetic Drawdown Testing

Selected Rain Gardens for Infiltration Testing

• St. Margaret Mary School (2 rain gardens)

• Niles Community Garden

• Hanover Park School (2 rain gardens)

• Park Forest Health and Tennis Club

• Roadside garden in Crystal Lake

• Homewood/Flossmoor High School

• Private Home, Wauconda, IL

• UI Research Farm• McCarty Park• And more!!!

Infiltration Testing Methods

• Single-Ring Infiltrometer– Filled to a depth of 38 inches with water– Time to infiltrate 19 inches and 38 inches

recorded

• Number of measurements– <400 ft2 = 3 per garden– 400-1,000 ft2 = 5 per garden– >1,000 ft2 = # determined by field conditions

Preliminary Rain Garden Results

• Average infiltration times of 8.4 minutes to 22.2 minutes

• Significant variability observed within some rain gardens– West rain garden at St

Margaret Mary ranged from 6 minutes to 48 minutes

– West rain garden at Hanson Park ranged from 1.75 minutes to 22.25 minutes

Assessing porous pavement

• Visual Assessments– Setting and runoff

sources– Hydraulic Conditions

• Surface Infiltration Capacity Testing

Future Tool - Permeability Index

• Multiple Scales: Expand analysis, planning, application from site/parcel to community impact

• Performance-based targeting, assessment

• Address life-cycle cost of scenarios:The sustainable must be attainable

• Improve accountability:Only that which can be counted can be counted upon

• Identify and capture Green Infrastructure Capacity in highly urbanized landscapes (re-development)

Answering the Global Challenge

“It is this kind of project that needs to be replicated a billion times around the world.” -- Nobel Peace Laureate Wangari Maathai

Thank You

Bill Eyring

cnt.org/natural-resources

greenvalues.cnt.org

bille@cnt.org